This invention relates to a hot gas generating burner comprising: a nozzle discharging a fuel jet which then enters a mixing tube; an orifice plate surrounding the outlet of the nozzle; a casing divided by the orifice plate into an upstream-disposed precombustion chamber which includes the nozzle, and a downstream-located combustion chamber which contains the mixing tube; the orifice plate having a central passage for the fuel jet which is discharged from the nozzle, and a number of openings surrounding the passage, the openings being adapted for the combustion air to flow from the precombustion chamber into the mixing tube, wherein the openings are located within a surface which is defined by a projection of the clear cross-sectional area of the mixing tube onto the orifice plate.
Burners of the above-described type are known from, e.g. German Pat. No. 27 00 671 and German Offenlegungsschrift No. 29 18 416.
In these prior-art burners, air is supplied to the fuel that is fed through a centrally-disposed nozzle. The air is supplied through openings provided in an orifice plate that surrounds the nozzle. Air and fuel are mixed in a mixing chamber downstream from the nozzle, the mixing chamber being situated in a mixing tube. In operation, a flame front is formed in the area of the downstream end of the mixing tube. Hot gases from the flame front flow back outside the mixing tube to a recirculation port on the upstream end of the tube.
Such a burner design has been proven to ensure excellent combustion, which is, however, still associated with a relatively high noise level.
The object of the present invention is so to arrange the above burner that the noise generated in the operation of a burner of the above-defined art is reduced.